This invention relates generally to evaporative coolers. More particularly, it relates to an evaporative cooler drain pump to drain the evaporative cooler water reservoir, a controller that provides for improved performance of such a drain pump, and an evaporative cooler that employs such a drain pump.
Evaporative coolers are well known in the art and have enjoyed substantial favor over the years as devices for cooling and conditioning enclosed spaces in hot, arid regions such as the southwestern portion of the United States. Such coolers rely upon the principle that dry air forced through a medium that is wetted with water releases heat to evaporate some of that water, producing a stream of cooler, more humid air. Typically, the wetted media comprise cooling pads made of fibers of aspen or paperbased, fabricated material. As an alternative cooling system to refrigeration air conditioning, evaporative coolers consume much less energy and, as a result, have been the subject of interest in offsetting increasing costs of electrical energy associated with running an air conditioning system.
As is well known in the art, evaporative coolers typically use rotary or centrifugal blowers to draw ambient air through one or more wetted pads, delivering the evaporatively cooled air either directly or through a ducting system to the cooled space. The pads are typically wetted using a water distribution system that employs a recirculating pump for pumping water from a water reservoir, typically located in the bottom of the cooler, through hose or tubing to the pads. The water that is not evaporated from the pads during the evaporative cooling process is routed back to the water reservoir where it becomes available to be recirculated to the pads once again. As water from the system is lost to evaporation, it is typically replenished using a float valve or similar device connected to a water supply to deliver fresh water to the water reservoir.
As this evaporation occurs, the salts and minerals dissolved in the fresh water supply remain behind in the water distribution system and are recirculated from the reservoir over the pads and back to the reservoir. Additionally, dust and other particulates that may come in contact with the wetted pads tend to be washed into the water reservoir by the water flowing over and through the pads and become trapped in the water that is recirculated within the evaporative cooler. The result is a continuously increasing concentration of dissolved minerals and suspended solids and a continuously increasing salinity in the water used to wet the cooler pads. This increase in particulates, dissolved solids, and salinity results in the build-up of mineral deposits and scale on the evaporative cooler pads, the frames holding the pads, the recirculating pump, and other parts of the cooler. This scale build-up reduces the cooling efficiency of the evaporative cooler and shortens the operating lifetime of the recirculating pump, blower motor and cooler housing.
In order to slow the increase of dissolved solids, salts and other contaminants in the water used by evaporative coolers, a bleed system has been employed. This system continuously routes a small portion of the recirculated water to the drain of the cooler. Fresh water is continually added to the water distribution system to replenish the water that has been bled from the cooler. The addition of the fresh water to the water reservoir dilutes the concentration of salts and minerals in the cooler water. This method, however, wastes a substantial amount of water and is very undesirable. Alternatively, periodic maintenance whereby the water reservoir is manually drained via the reservoir drain has also been an approach used to maintain efficient cooler operation. This technique, however, is time-consuming and dirty for the person performing the draining, and is prone to being overlooked.
More recently, evaporative cooler manufacturers have employed a drain pump to periodically pump water from the water reservoir to the cooler drain, substantially removing the water containing dissolved solids and other contaminants from the water reservoir and allowing fresh water to replace the expelled water by way of the cooler's fresh water supply. U.S. Pat. Nos. 5,527,157 and 6,134,905 to Collins, et al., disclose such a system. The drain pump is a second pump present in the water reservoir and is controlled by an electromechanical timer. This timer monitors the amount of time the recirculation pump operates, and, after a pre-defined period of operation of the recirculation pump, activates the drain pump for a second pre-defined period of time, effectively replenishing the cooler water supply with fresh water as previously described. Typically, the timer that controls the drain pump operation measures six to ten hours of recirculation pump operation before activating the drain pump for a period of four to eight minutes.
Because these previous drain pump systems use electromechanical timers, they are subject to reliability issues and relatively higher manufacturing costs that are associated with mechanical timers. Also with these systems, problems arise during the installation and maintenance of the drain pump and timer system. In order to facilitate the testing of the drain pump during installation, the drain pump timer may be preset to the start of the drain cycle so that, upon the application of power to the drain pump, the draining action commences, verifying correct and proper installation to the installer. Configuring this preset condition is difficult, time-consuming, and expensive for the manufacturer. Many times, even if the manufacturer has preset the timer to begin the drain cycle upon application of power to the drain pump, the installer is not present at the cooler when power is applied to the drain pump. The installer is quite often inside the house or other area to be cooled when power is applied to the drain pump. The draining action is not witnessed by the installer, and verification of proper installation does not occur. Once the drain cycle has elapsed, the installer must wait for an extended period of time (the six to ten hour cycle) or leave and return to try to catch the drain cycle in progress. This is simply not practical. Additionally, anyone performing periodic maintenance on the evaporative cooler must be present at the drain pump during the drain cycle to verify the draining action, an inconvenient proposition at best.
Another problem that exists with prior drain pump systems is that they waste water because they drain the water reservoir twice if power to the drain pump is interrupted during the drain cycle. This results because the drain pump timer is powered from the same source as the recirculating pump, so that power is applied to the timer when power is applied to the recirculating pump. If the power to the recirculating pump is removed during the drain cycle, the drain cycle is interrupted. This can occur when the thermostat or other evaporative cooler controller shuts the cooler off during normal operation, or it can occur as a result of a general power outage at the cooler's location. Once the power is re-applied to the recirculating pump, the drain cycle will resume, even if the water reservoir was substantially drained prior to the power being removed from the recirculating pump. This results in an undesirable waste of water.
In view of the above discussion, there exists a need in the art for an apparatus and method that provides for improved draining of in an evaporative cooler. Accordingly, it is an object of the present invention to provide such an apparatus and method.
Another object of the invention is to provide such an apparatus and method that provides for manual activation of the drain cycle in an evaporative cooler.
Still another object of the invention is to provide such an apparatus and method that provides for an efficient usage of water in an evaporative cooler.
Yet another object of the invention is to provide such an apparatus that is suitable for use with evaporative coolers of various types.
Another object of the invention is to provide such an apparatus that is easily and inexpensively manufactured, easy to install and test and is reliable.
Additional objects and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by the instrumentalities and combinations pointed out in the appended claims.